The present invention relates generally to a lamp assembly for a UV spot curing system. More particularly, the present invention relates to a UV curing lamp assembly including a lamp, a reflector and a bracket adjustably supporting the reflector and the lamp.
It is well known to use UV lamps to cure certain curable compounds such as adhesives and the like. In situations where the compounds are deposited at precise locations with respect to a work piece, it is often necessary to provide a lamp which will spot cure the compound at the precise location.
Commercially available spot curing lamp assemblies typically include a UV lamp and a reflector. The UV lamp and the reflector are fixed relative to one another so as to accurately direct the UV energy emanating from the lamp. Conventional lamp assemblies include an elongate lamp having electrical terminals at opposite ends thereof. The lamp includes a radiation emitting portion such as the arc of a mercury vapor lamp positioned centrally between the ends of the lamp. Typically, such elongate lamps are mounted within a curved reflector with one end of the lamp supported at the base of the reflector and the other end of the lamp extending. outwardly therefrom. The end supported at the base of the reflector fixes the position of the lamp with the radiation emitting portion of the lamp being precisely positioned with respect to the reflector so as to maximize radiation output.
While mounting the lamp at only one end to the reflector affords a certain degree adjustability with respect thereto, it is difficult to fix the position of the lamp with respect to the reflector once it is accurately positioned. Further, mounting the lamp to the base of the reflector at one end, positions the opposite end of the lamp and its associated electrical terminal, in the path of the reflected radiation. This can interfere with the accurate radiation output as well result in reduction in the useful life of the lamp.
Further improvements in lamp assemblies are shown in U.S. Pat. No. 5,387,800. As shown therein, a prefocused lamp assembly includes a bracket which supports a reflector. The reflector includes a pair of opposed openings through its curved wall so as to accommodate the elongate lamp in a vertical orientation with respect to the reflector. The ends of the lamp extend through the holes in the reflector. The ends of the lamp are each fixed to the bracket by spaced apart cantilevered arms. Adjustability of the lamp with respect to the reflector is achieved by permitting movement of the reflector with respect to the bracket. Once the reflector is properly positioned with respect to the lamp, the base of the reflector is potted to fix the reflector to the bracket.
As may be appreciated, the lamp assembly shown in the ""800 patent is complex to manufacture. The lamp is held at both ends in a fixed position with respect to the bracket while the reflector is moved relative to the fixed lamp to provide the required adjustment. This arrangement makes it more difficult to accurately align the lamp with respect to the reflector. Once the precise position of the lamp with respect to the reflector is achieved, the reflector is permanently secured to the bracket. This prevents any further adjustment which may be necessary between the lamp and the reflector. As the reflector is permanently fixed to the bracket, the lamp and the reflector become essentially a unitary structure. Thus, once the reflector is attached to the bracket, the lamp itself is nonreplaceable. After the lamp is spent, the entire assembly must be replaced.
Moreover, when powered, these lamps generate a significant amount of heat. This heat tends to cause expansion of components of the lamp assembly. In situations where the lamp is fixed at both ends to a bracket, relative different rates of expansion of the components causes a significant force to be transferred to the lamp. This force could be damaging to the lamp. Certain relevant industry standards, such as those set forth by OSRAM/Sylvania, require that the lamp not be fixed at both ends.
It is, therefore, desirable to provide a UV curing lamp assembly where the assembly may be more economically and accurately manufactured and where the components of the assembly may be reused, disposing only of the lamp after it is spent.
The present invention provides a UV curing lamp assembly including an elongate UV lamp having opposed ends. The lamp includes electrical terminals at each of the opposed ends for applying electrical power to the lamp. The assembly further includes a reflector having a central base and a curved reflective wall extending from the base. The reflector includes a pair of opposed openings through the wall for passage of the opposed ends of the UV lamp therethrough. A bracket is adjustably supported to the reflector. The bracket includes a bracket body movably supporting a mounting member for adjustably supporting the base of the reflector to the bracket body. The bracket further includes a support arm extending from the bracket body so as to overlie one of the openings of the curved reflective walls. The support arm adjustably supports one of said opposed ends of the UV lamp with respect to the reflector.
In one embodiment of the present invention, one end of the lamp is removably secured in a lamp holder. The lamp holder is adjustably supported by the support arm to provide adjustable relative movement between the lamp and the reflector. The mounting member is an elongate member having the reflector mounted at one end thereof. The mounting member is slidably positionable with respect to the bracket body so as to permit adjustable movement of the reflector with respect to the bracket body. Movement of the mounting member with respect to the bracket body may be achieved under a spring bias.
The present invention thus provides for adjustable mounting of the lamp with respect to the reflector with adjustability in a first linear direction. Further, the mounting member provides for relative adjustable movement of the reflector with respect to the lamp in a second linear direction perpendicular to the first direction. Adjustment of the lamp with respect to the reflector in both directions provides for the operable positioning of the lamp with respect to the reflector so as to maximize radiation output.
In another embodiment the lamp may be positioned for adjustable movement in a third, substantially linear direction and mutually perpendicular to both the first and second linear directions.
Furthermore, by adjustably supporting the lamp to the bracket at only one end of the lamp, expansion of the components of the lamp assembly due to induced heat, will not transmit stresses to the lamp or the electrical connections maintained at each end of the lamp. Additionally, the bracket assembly of the present invention permits replacement of the lamp within the assembly after the lamp is spent.